I don't think either one is clear cut. Whitaker is a unicorn. He had more very good seasons than almost any infielder in history, but never had a great season. If someone thinks that great seasons are the qualification for HoF, then they wouldn't vote for Whitaker. That is fine as long as they are consistent. I put a lot of weight on career value and constency. Kent just doesn't have enough overall career value for me to say that he's clear cut. He is not the worst Hall of Famer, but I think he gets overrated because of his Bonds-aided RBI totals.
I don't think Whitaker is shunned just because of his personality. I think that voters just won't look beyond hits, homers, all-star games and world series titles.